1. Field of the Invention
This invention relates generally to a protective covering for a cable and, more particularly, to a removable protective covering for a wire rope sling having intertwined steel strands coated with a nylon coating that is used in the aerospace industry to lift spacecraft components when assembling the spacecraft in a high bay.
2. Discussion of the Related Art
Satellites, spacecraft, space vehicles and the like are typically constructed and assembled in a high bay. The high bay is maintained in a clean room environment so that particulates and other matter do not contaminate highly sensitive spacecraft components, for example, optical equipment, such as star trackers and the like. Because the satellite itself, and many components and parts of the satellite, such as deployment fixtures, are large in size and are heavy, sometimes on the order of several thousand pounds, strong cables and cable connections are required to lift, move and place these components for assembly. Because the satellite and its components typically cost millions of dollars, high integrity and reliable cables are required for this purpose.
Wire rope slings are currently being used in the industry to move the satellite and satellite components within the high bay. A typical wire rope sling is a cable that includes a plurality of intertwined steel strands wound in a predetermined configuration for different designs, and covered with a soft nylon coating that protects the wire strands from moisture and contamination, to prevent rust and the like, so as to preserve the integrity of the sling. The nylon coating is formed to the sling in such a manner that it is part of the sling and cannot be removed. Different sized slings having different lifting tolerances are available and include, for example, one-quarter, one-half and one inch diameter slings that are about 30 ft. long.
A problem exists with the current use of these types of wire rope slings that affects the clean room environment. When the sling is handled and stored during its normal use to move and assemble the satellite components, the soft nylon coating often becomes scraped and damaged, and nylon particles flake off of the sling causing contamination in the clean room. In other words, because the nylon coating of the wire sling is soft and is stored in a wound manner in a storage compartment, to be unwrapped and attached to connection hooks and the like in the clean room, the natural use and handling of the sling causes scrapes against the nylon coating that releases nylon particulate matter into the clean room environment. As the sling becomes older and more worn, the deterioration of the nylon coating increases. The sling is generally cleaned after use to reduce the nylon particulates. Because the slings are generally very heavy, 50-60 lbs., this problem is increased.
Currently, a new sling is purchased to replace a used sling that had a damaged nylon coating. However, because these types of wire rope slings can cost thousands of dollars, this cost is prohibitive. Other ways exist to prevent the nylon coating from being scraped and damaged, including wrapping the sling with a clean room approved tape. However, this solution also adds significant cost to the slings, and is not an effective solution. Further, proof load testing of the wire slings is performed on annual basis to monitor the integrity of the slings. Thus, any covering enclosing the nylon coating must be removed for visual inspection of the sling during the test.
What is needed is a sacrificial cover to protect the nylon coating of a wire rope sling to prevent contamination of a clean room environment from nylon particulates, where the cover is easily removable and is flexible to meet the storage requirements of the sling.